1. Statement of the Technical Field
The inventive arrangements relate to the field of RF antennas, and more particularly, to antenna pedestals.
2. Description of the Related Art
Oftentimes RF communication antennas are operated in environments which are not ideal. For example, it is common to find communication antennas mounted to mobile craft, such as aircraft, watercraft, automobiles and military vehicles, all of which experience some levels of vibration. Such vibration can induce beam radial errors in communication antenna reflectors, especially antennas which communicate via microwave signals having beam radiation patterns.
Vibration can include up to six acceleration components which interfere with antenna tracking. Specifically, the acceleration components include translational components along the x, y and z axes and rotational components about each of the three axes. Random vibrations typically are a composite of all six vibration components.
Vibration dampeners for absorbing vibration energy are known. However, simultaneously dampening of all six acceleration components has proven to be particularly difficult. For example, U.S. Pat. No. 6,695,106 to Smith et al. discloses a tunable vibration isolator for isolating a fuselage of a helicopter or rotary wing aircraft from other aircraft components, such as the engine or transmission. Smith's vibration isolator is of limited value, however, because it primarily dampens only a single translational component of vibration.
U.S. Pat. No. 6,471,435 to Lee discloses a flexural joint with two degrees of freedom. However, as noted, vibration can include up to six acceleration components. Thus, the flexural joint disclosed by Lee would not provide optimum vibration dampening for a communication antenna which is mounted onto a mobile craft.
U.S. Pat. No. 6,290,183 to Johnson et al. discloses a three-axis vibration device for use in a spacecraft vibration isolation system. The vibration device utilizes a plurality of dual-beam flexure isolation devices disposed between a payload and the spacecraft. Notably, the center of gravity of the payload is significantly offset from the flexure isolation devices. This arrangement results in a large moment of the payload mass relative to the vibration device. In consequence, the excitation response of the payload mass at the system resonant frequency will be high.